When such control input devices are used, for example, in motor vehicles to emit a variable signal to activate the brake system, then it is possible for this output signal to be either an electrical voltage or a fluid control pressure signal. Such fluid pressure may be either pneumatic or hydraulic. A control input device in this application is generally activated by the driver's foot. Furthermore, when the device is used in trucks, it must be designed for heavy duty operation.
Prior to the present invention, such a control input device is taught in the prior art in German Patent DE-OS 29 37 657. This device for brake activation includes a pedal which is mounted such that it can rotate in a bearing. This device also includes stops which provide a limit for the rotational movement of the pedal. In this particular device, the rotational movement of the pedal is transmitted by means of a tappet to the brake valve proper and there it is converted into a control pressure. Such control pressure being a function of the distance or force by which the pedal was displaced. Connected in a known manner to the brake valve is a potentiometer, which can be adjusted by the brake pedal. In this manner, an electrical output voltage which is a function of the adjustment to the potentiometer by the brake pedal, can be generated.
The control input device of the prior art, as described above, with all of the required bearings, linkages, springs, stops and other accessories, is relatively complex and difficult to maintain, in addition to being rather expensive.